Patent GB-191508561-A (GB)
Title: Improvements in Loud Speaking Telephone Systems and Apparatus.
Inventor: FORRESTER HAROLD JOSEPH CHARLE
IPC: H04M9/00
Filed: 1914-11-03
Granted: 1915-07-22
Abstract: 8561. Forrester, H. J. C., [International Callophone Corporation]. Nov. 3, 1914. Direct .- call systems and apparatus. - A telephone system for hotels &c. comprises loudspeaking telephones of the kind described in Specification 21,921/14 in the several rooms, which are connected to a central station, the operator of which announces the name of the person required in some or all of the rooms, and when this person announces his position, the operator disconnects ail the other rooms. The system comprises loud-speaking receivers 101 ... 104 connected in parallel, and sensitive transmitters 105 ... 108 connected in series, one receiver and one transmitter being arranged in each of the apartments of the hotel or club. The operator is provided with a transmitter 109, a receiver 110, switch 133, and a number of switches 113 ... 116, one for each loud-speaking telephone. Each of the switches 113 ... 116 consists of four springs 122, 117, 119, 121 mounted on an insulating - block 130, which is depressed when the lever 131 is raised, and a number of contacts 123 ... 129. Normally, the springs engage the contacts 123, 124, 126, 128; but when the lever of any one of the switches is raised, the contacts are broken, and the springs 117, 119, 121 engage the contacts 125, 127, 129. One terminal of each of the receivers is connected to the spring 117 of its switch by the lead 111, while the other terminal of each receiver is connected to the lead 226 by means of a lead 112. One terminal of each transmitter is connected to the spring 119 of its switch by the lead 118, while the other terminal of each transmitter is connected to the spring 121 by means of the lead 120. The fourth spring 122 normally engages the contact 123. The switch 133 comprises two springs 138, 139 normally engaging contacts 140, 141, from which they are separated by the operation of the lever 134. When the operator wishes to communicate with all the compartments, the receiver 110 is removed from its hook 142, thereby establishing a circuit containing the battery 143, the primary winding 144 of an induction coil, and the transmitter 109. The receivers 101, 102 are connected in parallel across the lead 226 and the terminal 155 as follows : lead 112, receiver, lead 111, spring 117, contact 124. lead 151. spring 139, contact 141, lead 152. The circuit of the receiver 104 is as follows : leads 112, 111, spring 117, contact 124, lead 153, spring 138, contact 140, lead 152; while the circuit of the receiver 103 is completed direct from the contact 124 by means of the lead 154. The circuits of all the receivers are completed from the terminal 155 as follows: contact 123, spring 122 of each of the switches 113 ... 116, lead 156. When the called person indicates his whereaborts to the operator, say the lobby, the operator depresses the lobby switch 115, thereby opening all the receiver circuits at the spring 122 and contact 123 of the switch 115 and establishing a new circuit for the receiver 103 as follows : lead 111, spring 117, contact 125, lead 157. The receiver 104 is cut out of circuit by depressing the lever 134 of the switch 133, thereby breaking the circuit of this receiver at the spring 138 and contact 140, while the receivers 101, 102 may be cut out by raising the lever 134 of the switch 133. When the operator's switches are in the position shown, all the transmitters 105... 108 are connected in series with the primary winding 149 of an induction coil 149, 150 through the lead 159 and the spring 119 and contact 126 in the connexions of the switches, and when the person required has been located. the switch corresponding to his telephone is depressed, whereupon all the other transmitter circuits are broken and a new circuit established for the called person transmitter as follows: lead 164, contact 127, spring 119, transmitter, spring 121, contact 129, lead 165.